Field of the Invention
Embodiments of the invention relate to memory access. More specifically, embodiments of the invention relate to memory access in a T type memory topology for dual inline memory modules.
The field of the invention is that of electronic music equipment. More precisely, the invention relates to a device for controlling an audio or video signal, and an electronic mixing controller implementing such a control device.
Background
Electronic mixing controllers or consoles are widely used by professional or amateur DJs (abbreviation of disc-jockey) or VJs (abbreviation of video jockey) to select and play pieces of music in discotheques or at an evening party, and to interact with these pieces of music (and where applicable with a visual accompaniment, such as images, videos, or visual effects), in particular to accelerate, slow down and/or repeat a portion (these processing operations are called “mixing”).
These electronic mixing controllers or consoles are an alternative or a complement to vinyl turntables (or record players). They can furthermore be used to mix audio-video clips or to synchronize music with video (or vice versa).
There are relatively compact mixing consoles which can be easily transported. Some of them can be connected to a data-processing apparatus, a laptop computer, for example, on which a mixing software program is implemented, for example, the “Virtual DJ” (registered mark) software from the firm Atomix Productions which is capable of mixing audio and video tracks. With this software, it is possible to perform scratching with the video in the same way as with audio only, i.e. with the same impact on the sound track of the video clip as if a soundtrack having no visual accompaniment were to be mixed.
Conventionally, a mixing console comprises a control surface on which there are means for controlling, such as, for example, rotary buttons, push buttons, faders, used for setting the audio signals (in terms of equalization, volume, balance, gain, etc.).
One or more jog wheels or jog dials are also provided. A jog wheel of this kind enables the user to move within musical libraries or within a piece of music, or else accelerate or slow down the playback of a piece of music.
During the playback of a piece of music, a pressure exerted by a user on the jog wheel enables the creation of sound effects known as a “scratch” sounds, as when a DJ places his hand on a vinyl microgroove record when it is being played on a record player (thus interrupting its rotation), and moves the record forward and backward. A portion of the music is then played forward and backward with the hand (the vinyl record rotates at the speed of the hand instead of rotating at the speed of the turntable of the record player) which produces specific sounds.
There are different types of scratch. As such, it is important to note that the gestures of the hand during the scratch correspond to relatively rapid actions, therefore to a relatively rapid rotation of the jog wheel.
The computer has imposed itself in the DJing environment in the same way as the CD player or the vinyl record player.
However, using a computer in parallel with a mixing console required for the DJ to often look at the screen of the computer instead of looking at the audience or his hands during the settings. In particular, the DJ is constrained to regularly look at the screen of the computer to read at what speed a piece of music is being played, how much time remains before the end of a piece of music, or, when he is performing a scratch, to retrieve the position of the beginning of the scratch. Using a computer therefore has the disadvantage of seizing the attention of the DJ. Furthermore, the display on the screen of the computer comprises a latency. In particular, the position of the jog wheel displayed on the screen of the computer differs with respect to the actual position of the jog wheel actuated by the DJ. Between the moment when the DJ displaces the jog wheel and the moment when the screen displays the displacement that the DJ sees on his mixing console, there is a difference that is visually noticeable and which can disturb the DJ (i.e. have him miss the position that he wants to reach). Indeed, currently, the latency is from five to ten milliseconds. Consequently, for rapid and precise actions such as performing a scratch, the DJ cannot rely on what is displayed on the screen of the computer.
Moreover, it is desirable that the mixing console should detect such scratching on the part of the user, i.e. the action of the hand or fingers of the user on the jog wheel and display the corresponding information.
Some Pioneer CD players (registered trademark) and Pioneer mixing controllers have either a circular screen built into the player or the mixing controller, or a chase (i.e. a lighted crown of LEDs (“Light-Emitting Diode”) whereon luminous points (or a LED) indicate the angular displacement of the plate of the jog wheel.
The implementing of a lighted crown (of LEDs in particular) or of a circular screen however has several disadvantages.
The size of the chase or of the screen limits the precision of the angular information. By way of example, a chase that comprises 36 LEDs, displays one LED every ten degrees in order to represent a displacement over 360 degrees. Such a chase therefore does not make it possible to display an angular displacement to the nearest 5 degrees. Even so, displaying an angular displacement to the nearest 5 degrees would offer precision that is much less than that offered by a point of Tipp-Ex (registered trademark) placed on a vinyl record by a DJ in order to allow him to get his bearings when he is performing a scratch on a record player. Furthermore, the resolution of the screen limits the precision of the visual information.
Moreover, the size of the chase or of the screen built into the mixing console limits the readability of the information.
Indeed, even if a high-definition screen is available, or a chase comprising 72 LEDs, if the screen or the chase is not large, a reduced angular displacement can hardly be discerned for the user. The precision depends on the number of LEDs or on the resolution of the screen. However, if the screen is of reduced size (for example, when it is built into a jog wheel of a mixing console), it is difficult to indicate the angular position with a precision that exceeds 5 degrees, because the user would have to be able to identify the separations of the circle in 1/72, which requires a trained eye; all the more so as the angular displacements represented on the screen or the LEDs are rapid and that a mixing console is used in a difficult visual environment (dark room with plays of lights).
Finally, the display is not practical. It is possible to change the resolution of the angular displacement on the chase or on the screen in order to render a minimal displacement more readable, for example by multiplying the angular displacement of the plate on the display by four. As such, when the user displaces the plate 10°, he moves his representation on the screen or on the chase by 40°. The screen then gives information that is more precise but not very practical, since the user cannot get his bearings on the screen in order to aim for a position (indeed, the angular displacement displayed on the screen no longer corresponds to the angular displacement of the plate).
Moreover, currently, the measurement of the angular displacement of the jog wheel is carried out using optical discs or wheels. The jog wheels of DJ products generally use optical encoders (more or less precise).
The main limitation with this type of technology is the resolution. Indeed, the higher the number of steps per revolution is, the more the costs increase. This can be explained by the fact that it is necessary to either:                use finely laser-cut circular metal discs in order to have very fine steps of rotation (counting of the teeth);        use discs made of transparent polymers with fine printed lines in order to obtain a precise counting (large number of lines);        use a reduction ratio in order to increase the precision of the counting of a less-precise encoder.        
In any case, this requires the adding of additional mechanical parts or the use of expensive parts (discs).
Currently, in order to be able to simulate the scratch mode of a vinyl turntable, a portion of the jog wheel is pushed in mechanically under the weight of the hand of the user. The detection of the pushing-in movement of the jog wheel is either mechanical (with the pressure making it possible to actuate a sensor), or optical (through an infrared emitter and receiver, for example). The pushing in of the plate of the jog wheel provides a sensation close to the microgroove record turntables, where the weight of the hand pushes in the thickness of the felt placed between the vinyl record and the plate, which immobilizes the microgroove record.
The Pioneer CDJ CD players operate on this principle. The plate is pushed in over a course of travel less than 1 mm under the weight of the hand, with a lever multiplying the movement caused by the pushing in of the plate in order to displace a tab bearing white and black streaks. An optical sensor captures this displacement of the streaks and as such informs the microcontroller of the pushing in of the plate. This technique makes the jog wheels mechanically more complex (and therefore expensive) than a weight or capacitive detection.
The display tends to become complex for the user and the information is supplied in a manner that is not very natural.
In other terms, the existing mixing consoles do not provide full satisfaction, and there exists therefore a need for a mixing console that minimizes or cancels out the disadvantages of the devices of prior art.